Phosphorescent marine products

ABSTRACT

In one embodiment of the invention, a marine article of the invention includes a phosphorescent phosphor. A particularly advantageous phosphorescent phosphor comprises MAl 2 O 4 . As used herein, “M” is at least one cation selected from a group consisting of calcium, strontium, and barium. The phosphor comprises 0.001% to 10% of a europium activator, and 0.001% to 10% of at least one dopant selected from the group consisting of lanthanum, cerium, praseodymium, neodymium, samarium, gadolinium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, tin and bismuth as a co-activator, in terms of mol % relative to the metal element expressed by M. The phosphorescent marine article has an afterglow corresponding to a luminance of at least 0.3 mCd/m 2  for at least 420 minutes.

This application is a continuation of application Ser. No. 10/791,363,filed Mar. 1, 2004, which is a continuation of application Ser. No.09/778,973, filed Feb. 6, 2001, which is a continuation of applicationSer. No. 09/152,377, filed Sep. 14, 1998, now U.S. Pat. No. 6,253,698,which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

During recent years, maritime activities both commercial andrecreational have increased dramatically. As a consequence, visibilityof marine articles is more important as U.S. bodies of water becomecrowded. The current means of increasing visibility of marine articles,such as, for example, buoy markers and boat indicators, includephosphorescent or fluorescent materials and brightly colored paints.However, these current means suffer from serious visibility anddurability challenges.

Generally, the afterglow time of a fluorescent substance is short, i.e.,the light emitted from the fluorescent substance decays immediatelyafter removal from the source of excitation. Unlike such a fluorescentsubstance, some substances emit light after having absorbed ultravioletradiation, and afterglow thereof that can be visually observed for aconsiderable time (ranging from several tens of minutes to severalhours) after the source of stimulus is cut off. Such substances arecalled phosphorescent phosphors.

Phosphorescent phosphors are known. Sulfide phosphorescent phosphors arealso known and include for example CaS:Bi (which emits light of violetblue), CaStS:Bi (which emits light of blue), ZnS:Cu (which emits lightof green) and ZnCdS:Cu (which emits light of green) and ZnCdS:Cu (whichemits light of yellow or orange). However, many of these sulfidephosphorescent phosphors are chemically unstable and show degraded lightresistance, i.e., they suffer from problems that must be solved forpractical use.

The most extensively used phosphorescent phosphor among such sulfidephosphorescent phosphors is zinc sulfide phosphorescent phosphor(ZnS:Cu). However, zinc sulfide phosphorescent phosphor is decomposed asthe result of irradiation by ultraviolet radiation in the presence ofmoisture and thus, over time, blackens or reduces the phosphor'sluminance. Therefore, it is difficult to use this phosphorescentphosphor in fields where it is placed outdoors and exposed to a directsunlight, that is, application is limited to luminous clocks/watches orclocks/watches and instrument dials, evacuation guiding signs or indoornight-time display.

Even when zinc sulfide phosphorescent phosphor is used for a luminousclock, the afterglow allows the time to be visually recognized lastsonly from 30 minutes to 2 hours. Therefore, the phosphorescent phosphormust be doped with a radioactive substance and a self-luminous paint tokeep emitting light by absorbing the energy of radiation from theradioactive substance.

The use of brightly-colored paints, including fluorescent paints, onmarine floats do not solve the visibility problem in darkness.Brightly-colored and fluorescent paints can only be seen if light ispresent to be reflected thereby. Also, these paints become eroded orworn from the relatively soft and pliable surface of microporousresinous or foam marine floats, during use, so that any advantage whichjustifies the expense of applying such a paint is soon lost or severelydiminished.

Thus, a need exists to develop phosphorescent marine products thatprovide long lasting afterglow characteristics, are chemically stableand physically durable in an outdoor marine environment.

SUMMARY OF THE INVENTION

The invention solves the prior art's visibility and durability problemsof marine products by developing a highly visible and durable marinecompatible product. In one embodiment, a marine article of the inventionincludes a phosphorescent phosphor. A particularly advantageousphosphorescent phosphor comprises MAl₂O₄. As used herein, “M” is atleast one cation selected from a group consisting of calcium, strontium,and barium. The phosphor comprises 0.001% to 10% of a europiumactivator, and 0.001% to 10% of at least one dopant selected from thegroup consisting of lanthanum, cerium, praseodymium, neodymium,samarium, gadolinium, dysprosium, holmium, erbium, thulium, ytterbium,lutetium, tin and bismuth as a co-activator, in terms of mol % relativeto the metal element expressed by M. The phosphorescent marine articlehas an afterglow corresponding to a luminance of at least 0.3 mCd/m² forat least 1000 minutes. In a preferred embodiment of the invention thephosphorescent phosphor is incorporated into a polymer forming aphosphorescent buoy or dock post cap.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a perspective view of a marine cap.

FIG. 2 is a front elevation view of a marine cap.

FIG. 3 is a top plane view of a marine cap.

FIG. 4 is a bottom plane view of a marine cap.

DETAILED DESCRIPTION

A marine article includes a phosphorescent phosphor. A disclosure of oneexample of a phosphorescent phosphor suitable for a marine product ofthe invention is patent number 5,424,006 incorporated by referenceherein. The phosphorescent marine articles described below show muchlonger afterglow characteristics that last longer than presentlyavailable phosphorescent marine articles and are chemically stable inthe presence of moisture and UV light (marine environment).

It is important the marine article be visible throughout an entire nightof darkness. This insures that marine articles are able to be seen andto alert aquatic users to dangers the marine articles are marking evenin darkness. Typically the marine articles should display a visibleafterglow for at least about seven-eight hours (420-480 minutes),preferably greater than about ten hours (600 minutes), more preferablygreater than about 1000 minutes. This length of time is adequate for atypical summer period of darkness for most regions. However, longerafterglow periods of time are desirable.

The Phosphorescent Phosphor

One phosphorescent phosphor suitable in the invention is knowncommercially as “Luminova”. “Luminova” is manufactured by Nemoto & Co.,Ltd., of Japan. The present invention provides a phosphorescent phosphorwhich comprises a compound expressed by MAl₂O₄ whose host material is acompound in which M is at least one cation selected from a groupconsisting of calcium, strontium and barium.

A phosphorescent phosphor which includes a compound expressed by MAl₂O₄whose host material is a compound composed of a plurality of metalcations in which M is at least one metal cation selected from a groupconsisting of calcium, strontium and barium to which magnesium is added.

The phosphor contains 0.001 mol % to 10 mol % of a europium activator interms of mol % relative to the cation expressed by M. The phosphor alsotypically contains 0.001 mol % to 10 mol % of at least one dopantselected from a group consisting of lanthanum, cerium, praseodymium,neodymium, samarium, gadolinium, terbium, dysprosium, holmium, erbium,thulium, ytterbium, lutetium, manganese, tin and bismuth as aco-activator in terms of mol % relative to the metal element expressedby M.

The phosphorescent phosphor may show a glow peak of thermo-luminescencein a high-temperature region of 50° C. or above when irradiated byultraviolet or visible rays having a wavelength of 200 to 450 nm at roomtemperatures. The phosphorescent phosphor's afterglow remains visiblefor at least 1000 minutes. Visible is defined as a light intensitycorresponding to a luminance of about 0.3 mCd/m².

The Marine Article

The Applicants have found the above described phosphorescent phosphoruseful in a variety of marine articles. Examples of marine articlesinclude dock accessories, boat accessories, personal accessories, andfloatation devices. Virtually any article that relates to outdoor wateractivities is useful in the invention.

One particularly useful marine articles are phosphorescent marine caps.Marine caps include buoy caps and dock post caps. These marine caps canmount on top of the buoy or dock post body. FIGS. 1-4 illustrate oneembodiment of a preferred configuration of a marine cap. The overallappearance of the embodiment illustrated in FIGS. 1-4 is not exhaustiveof appearances which are within the scope of the invention but aremerely representative of one configuration which is ornamental butmaintains some or all of the functional aspects of a marine cap of theinvention.

Dock Accessory

Dock accessories are articles that are used in conjunction with theconstruction, operation, and maintenance of a dock or pier. An listingof dock accessories includes, for example, dock fenders, post fenders,bumpers, dock trim, step trim, cleats, ladders, post caps and docklights.

Boat Accessory

Boat accessories are articles that are used in conjunction with theconstruction, operation, and maintenance of a boat, ship, or personalwater craft. An listing of boat accessories includes, for example,bumpers, sails, masts, lettering, numbering, marine rope, trailerguides, trailer rollers, ladders, covers, shift knobs, throttle knobs,steering wheels and instrument gauges.

Personal Accessory

Personal accessories are articles that are used in conjunction with theperson while in a marine environment. An listing of personal accessoriesincludes, for example, jackets, knives, coolers, drinking glasses, toolsand patches.

Flotation Device

Flotation devices are articles that have the ability to stay on thesurface of water. A listing of flotation devices includes, for example,buoys, buoy wraps, buoy caps, life jackets, floating key rings, ringbuoy/life savers and floating cushions.

Tape

The phosphorescent phosphor can be incorporated into a tape. The tapecan be affixed to a marine article using known methods. The tape can bea multi-layer film typically consisting of a phosphorescent backing, anadhesive and a liner.

Polymer

The phosphorescent phosphor can be incorporated into a polymer. Anlisting of useful polymers includes, for example, polycarbonates,polyethylenes, polypropylenes, polystyrenes, polyurethanes, copolymersof ethylene, copolymers of vinyl acetate, terpolymers of acrylonitrile,terpolymers of butadiene and terpolymers of styrene.

The manufacturing process for polymeric marine articles is typically avacuum\thermoforming process although other methods are known in theart. The phosphorescent phosphor can be mixed with the liquid polymer toform the phosphorescent phosphor/polymer mixture. The plastic can thentypically be formed into sheets. The sheets are heated and placed over amold. A vacuum pulls the sheet around the mold to form the marinearticle. Finally, the article is hardened by cooling the polymer. Thephosphorescent phosphor/polymer mixture may also be formed into pelletsthat are extruded and further processed into the marine article usingknown methods. Injection molding is another common process for formingthe marine articles of the invention.

The phosphorescent phosphor can also be incorporated into a paint suchas a polyurethane paint. The phosphorescent phosphor paint may then beapplied to the marine article to provide the luminance quality usingknown methods.

The above specification, and figures provide a complete description ofthe composition of the invention. Many embodiments of the invention canbe made without departing from the spirit and scope of the invention.

1. A phosphorescent marine product comprising; a marine article; and aphosphorescent phosphor; wherein, the phosphorescent phosphor comprisesMAl₂O₄ wherein M is at least one cation selected from a group consistingof calcium, strontium, and barium, wherein the phosphor comprises 0.001%to 10% of a europium activator, and wherein the phosphor comprises0.001% to 10% of at least one dopant selected from the group consistingof lanthanum, cerium, praseodymium, neodymium, samarium, gadolinium,dysprosium, holmium, erbium, thulium, ytterbium, lutetium, tin andbismuth as a co-activator, in terms of mol % relative to the metalelement expressed by M.
 2. The phosphorescent marine product of claim 1,wherein the phosphorescent phosphor is incorporated into a tape and thetape is affixed to the marine article.
 3. The phosphorescent marineproduct of claim 1, wherein the marine article comprises a polymer andthe phosphorescent phosphor is incorporated into the polymer.
 4. Thephosphorescent marine product of claim 3, wherein the polymer isselected from the group consisting of polycarbonate, polyethylene,polypropylene, polystyrene, polyurethane, copolymer of ethylene,copolymer of vinyl acetate, terpolymer of acrylonitrile, terpolymer ofbutadiene and terpolymer of styrene.
 5. The phosphorescent marineproduct of claim 1, wherein the phosphorescent phosphor is incorporatedinto a paint and the paint covers at least a portion of the marinearticle.
 6. The phosphorescent marine product of claim 5, wherein thepaint comprises polyurethane.
 7. The phosphorescent marine product ofclaim 1, wherein the marine article is a dock accessory selected fromthe group consisting of dock fenders, post fenders, bumpers, dock trim,step trim, cleats, ladders, post caps and dock lights.
 8. Thephosphorescent marine product of claim 1, wherein the marine article isa boat accessory selected from the group consisting of bumpers, sails,masts, lettering, numbering, marine rope, trailer guides, trailerrollers, ladders, covers, shift knobs, throttle knobs, steering wheelsand instrument gauges.
 9. The phosphorescent marine product of claim 1,wherein the marine article is a personal accessory selected from thegroup consisting of jackets, knives, coolers, drinking glasses, tools,and patches.
 10. The phosphorescent marine product of claim 1, whereinthe marine article is a floatation device selected from the groupconsisting of buoys, buoy wraps, buoy caps, life jackets, floating keyrings, ring buoy/life savers and floating cushions.
 11. A phosphorescentmarine product comprising; a buoy cap or a dock post cap; and aphosphorescent phosphor; wherein, the phosphorescent phosphor comprisesMAl₂O₄ wherein M is at least one cation selected from a group consistingof calcium, strontium, and barium, wherein the phosphor comprises 0.001%to 10% of a europium activator, and wherein the phosphor comprises0.001% to 10% of at least one dopant selected from the group consistingof lanthanum, cerium, praseodymium, neodymium, samarium, gadolinium,dysprosium, holmium, erbium, thulium, ytterbium, lutetium, tin andbismuth as a co-activator, in terms of mol % relative to the metalelement expressed by M.
 12. A phosphorescent marine product comprising;a marine article; and a phosphorescent phosphor; wherein, thephosphorescent phosphor has an afterglow corresponding to a luminance ofat least 0.3 mCd/m² for at least about 420 minutes.
 13. Thephosphorescent marine product of claim 12, wherein the phosphorescentphosphor is incorporated into a tape and the tape is affixed to themarine article.
 14. The phosphorescent marine product of claim 12,wherein the marine article comprises a polymer and the phosphorescentphosphor is incorporated into the polymer.
 15. The phosphorescent marineproduct of claim 14, wherein the polymer is selected from the groupconsisting of polycarbonate, polyethylene, polypropylene, polystyrene,polyurethane, copolymer of ethylene, copolymer of vinyl acetate,terpolymer of acrylonitrile, terpolymer of butadiene and terpolymer ofstyrene.
 16. The phosphorescent marine product of claim 12, wherein thephosphorescent phosphor is incorporated into a paint and the paintcovers at least a portion of the marine article.
 17. The phosphorescentmarine product of claim 16, wherein the paint comprises polyurethane.18. The phosphorescent marine product of claim 12, wherein the marinearticle is a dock accessory selected from the group consisting of dockfenders, post fenders, bumpers, dock trim, step trim, cleats, ladders,post caps and dock lights.
 19. The phosphorescent marine product ofclaim 12, wherein the marine article is a boat accessory selected fromthe group consisting of bumpers, sails, masts, lettering, numbering,marine rope, trailer guides, trailer rollers, ladders, covers, shiftknobs, throttle knobs, steering wheels and instrument gauges.
 20. Thephosphorescent marine product of claim 12, wherein the marine article isa personal accessory selected from the group consisting of jackets,knives, coolers, drinking glasses, tools, and patches.